Why does Dropbox show sync of files that are not mine ?

Why does Dropbox show sync of files that are not mine ?

In the image below, the top item is my file,
the others ex. i-didnt-feel-appreciated--blabla, etc are not mine.

However when checking my Dropbox folder, the spam files are not there,
they only appear in my sync list.
My concern is that it displayed sync of ca 2000 spam files that are not mine.

Is this a known bug or some new issue with Dropbox ?

A common cause of this is Unlinking a Dropbox account with a system, and then linking it with another. When doing this, the user is prompted if they wish to reuse the existing folder. If this is done, any remaining content from the older user is merged into the new user's account.

Since the comments suggest you cannot actually find any files and they don't show on the Dropbox website, there's the possibility that stray metadata or other hidden information is throwing off Dropbox with these files. An easy to way rule this out is to simply uninstall Dropbox and reinstall, as well as ensure the folder it uses is deleted and created fresh (make sure to back up anything of yours there first).